[Harp-L] Curvature of the mouthpiece

[Vern]

Bend the mp after machining and polishing but before plating.

Bend the mp by clamping it against a curved form.  Mark the form on a piece of wood with a compass and cut with a bandsaw.

Compute the radius of curvature (R) of the old mp as follows:

L = length of mp measured with a straight ruler on the chord of the curve.
D = depth of the curve at the midpoint of the mp.
R = radius of the curve.

R = L * L / 8 / D  +  D / 2
You can ignore the D/2 term for harmonica mouthpieces where the curve is shallow.

Thus R = L * L / 8 / D

The radius of the form will have to be less than the radius of the resulting mp curve to account for spring-back of the metal.  Start with 90% of the desired curve radius and then cut-&-try smaller radii until you get the desired mp curve.

Vern


> On Jul 3, 2016, at 9:15 PM, Li Leon <leon.issac.li at xxxxx> wrote:
> 
> Hi experts,
> 
> One of my friend is kindly offered to make me some mouthpieces, to replace
> me worn and not so comfortable old ones.
> 
> Just wondering whether anyone knows by any chance how the curvatures on the
> these mouthpieces are formed and whether it is pre or post milling/molding.
> 
> Also, what thickness would be the standard/recommended for the coating, I'm
> getting quote for silver plating but the price seem to vary quick a bit as
> the thickness increase.
> 
> Any information on the above points is greatly appreciated!
> 
> Thanks in advance!
> 
> Cheers,
> 
> Leon